8BA & 8RT engines in LP Bren Gun Carriers

[ajmac]

There isn't a lot of point really.

Get a wartime 81 or a 59AB, these are the wartime 239ci and the postwar 239ci, externally they look identical, centre water outlet, same water pump castings, same bell housing and cam mounted distributor, the 59AB has an slightly higher CR and modified block casting internals for improved cooling, but only a little I think.
An 8BA did have improved cooling passages and modern rod bearings, but most of the redesign was a cost down rather than improvement. If you use one, you can get an adaptor plate to use the wartime gearbox, you will need wartime water pumps as the pump casting is different on the 8BA putting the engine mounts in the wrong place. You would need pre 8BA heads (24 stud) and an earlier front cover to use the original wartime distributor, which would mean changing the cam as I think the nose I'd different...in the end you would only be using the short block.
The 'best' engine would be a French 1990s flathead with pre 8BA everything else. When I say short block I include the valve train, 8BA valve gear is much better than pre 8BA as far as fitting and service goes.
All flathead distributors are terrible compared to the last of the line of distributors before full management came in, so having the side mounted unit would not be any better than the front unit, best would be to replace with a later chev or something that has both centrifugal advance and vacuum advance for better combustion at part load.

[peter simundson]

An excellent explanation. Clear, concise and professional.

Peter S

[Marc van Aalderen]

Originally Posted by ajmac

The 'best' engine would be a French 1990s flathead with pre 8BA everything else.

I have a French engine in my Universal and boy does she fly! Last Race to the Bridge in Arnhem we were clocked at 40 Mph trying to keep up with the rest, mainly Jeeps. Had a crew of 10 and a 6 Pounder on tow. Mind you, I did blow a gasket and spray engine coulant all over. My own fault off course. Still need to get my speedo and temperature gauge working.....

Cheers,

[ajmac]

Yes Marc, I noticed you had a French unit in a photo you posted a few days ago. Looked good

[cletrac (RIP)]

For the "best" forties flattie with all stock parts start with a 46 to 48 Canadian truck engine. They had higher compression and a better camshaft for operating at our higher altitude. Then get a 49 or up 255 Merc engine and put the crank and pistons in the truck engine. You need to change to the 239 crank gear so it'll work with the 48 camshaft since the gears are cut the opposite way. Bolt all the older accessories on and you'll have a 140 hp flattie that looks and sounds original. Oh, and Ford didn't use a 12 volt system until 1956 so flatties wouldn't have got them.

[Richard Farrant]

Originally Posted by cletrac

. Oh, and Ford didn't use a 12 volt system until 1956 so flatties wouldn't have got them.

Except the wartime British Ford WOT series of military trucks, the full 12 volts on their flatheads !

[RichardT10829]

I thought the speed was limited by the gearing not the engine ? if you want to go faster put a taller final drive in the gearbox... or a taller crown wheel in the diff...simple...your gauge will no longer be accurate but hey ho......... remember folks the speed limit in the UK for carriers is now 20mph.... would hate to stop one in a hurry at 40...it just wont happen. personally if i was going to build a modded unit for a carrier i would aim for something that has plenty of bottom end grunt and plenty of torque for static neutral turns etc..... thats just me though

[Darrin Wright]

Thank you all for the wealth of information.
It has shown me that I still have a lot to learn.
It is a bit hard to find info on wartime vehicles and engines, I had a thought that the V8 in the carriers was 100hp but could not find a reference to/for it.

In hindsight I should have mentioned why I was looking at the later engines. I thought a little more hp would really help the carrier, I also wanted something that was more maintainable with the distributor easily got to for timing and adjustments.

I think my way forward is to get a 100hp wartime engine (whick my Dad has several) and rebuild it with some internal improvements from Flatattack racing (adjustable cam followers/lifters, modern water pumps, thermostats) and also an electronic distributor (Pertronix electronic ignition is one of many out there). Also an upgrade to a 12 volt system for starting and lighting would assist.

Thanks

[shaun]

I fully agree with Richie, I dont see what the need for speed is with carriers, power and torque to pull you through the mud and up hills yes !!! but carriers are not good at speed things soon get out of control, as my old father says "any fool can drive a big car fast in a straight line" . may as well chrome the heads at the same time. ive probably said to much

[Stew Robertson]

Just put the merc 100 hp in and tune it and it will get at least 40 plu Leave every thing original but the cam.
With the cam and tuned you will get the horses and the RPM
Take it from a guy who has done it
and no one only you will know it is not original

Stew